Digital Photo Tip: Tack Sharp

Nature and landscape photographers have always aspired for highly focused and visibly “sharp” images. Digital photography has many of the same challenges and solutions as film for creating the sharpest images, plus a few additional ones as well. With any camera there are some tried and true ways to capture sharp images. Of course the quality of your camera’s lens and proper focusing techniques are major factors. Using a tripod to eliminate camera motion or vibration and shooting with the smallest possible aperture (shutter opening) to gain the greatest focal depth are two other time honored techniques for getting sharp images. For slow shutter speeds using a cable release or timer to activate the camera allows you to avoid touching it and causing vibrations. Higher end SLR cameras often have a mirror lock setting so that the viewfinder mirror can be locked before the shutter opens. The movement of the mirror in SLRs can cause enough vibration in the camera to affect sharpness at shutter speeds between about 1/10 of a second and 2 seconds.

All of these techniques work well with both film and digital capture. Digital cameras introduce some new considerations for creating sharp images, however. The human eye recognizes sharpness as crisp lines along edges. When digital cameras evaluate the information captured by their sensors and try to assemble it into a realistic picture there is a slight amount of blending of colors along edges making the image appear less sharp. When shooting in jpeg capture mode, most digital cameras will automatically apply some “digital” sharpening along edges to counter this affect. Many cameras allow the user to preset how much sharpening the camera will apply. If simple in-camera sharpening is what you are looking for, consult your user’s manual to find out how to adjust the amount of sharpening that is applied. When shooting in RAW capture mode, no sharpening is added to the image at all. Whether shooting in RAW or jpeg mode, I prefer to apply my sharpening later with photo editing software like Photoshop because it offers more control and better quality. There are many different digital tools for enhancing the sharpness of your photos. In Photoshop my favorite is “unsharp mask” found in the filters menu. It can be a little tricky to figure out, but I find that a higher amount (80-200) and smaller radius (.5 –1.5) with the threshold set to 0 or 1 works well for a final sharpening pass right before printing. You need to experiment a bit to get it right. To really see the effect of the sharpening, view the image at 100%. Be careful not to over sharpen giving your image unnatural halos and a plasticized look. When used to prepare an image for printing, email or web use, it is best to apply the unsharp mask filter at the end of the editing process. Resizing and making other adjustments after sharpening can decrease sharpness and even cause loss of quality. For this reason it is also important not to save an image with final sharpening applied. Instead, apply sharpening to fit the desired output size, purpose and use each time you print or email an image. Then close the image without saving it in its sharpened state, or save it with a new name if you plan to use it in that exact format again.

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